1. Field of the Invention
The present invention is directed to a medical perfusion system adapted to handle the selective oxygenation, filtering and recirculation of blood in connection with various medical procedures. In particular, the present invention relates to controlling pumps in the perfusion system.
2. Background Information
The present invention is directed to a medical perfusion system adapted to handle the selective oxygenation, filtering and recirculation of blood in connection with various medical procedures. A conventional perfusion system may be used to oxygenate, filter, and/or recirculate the blood of a patient during a medical procedure. Such a perfusion system may have a fluid conduit that removes blood from the patient during the medical procedure, a separate fluid conduit that returns blood to the patient, one or more blood pumps that pump blood through the conduits, and a plurality of sensing devices, such as flow sensors and/or level sensors associated with blood pumps. The perfusion system may also include air embolus sensors, temperature sensors, flow occluders, etc. Typically, a perfusion system is provided with a configuration specifically designed to be used for a particular purpose. For example, one perfusion system may be specifically designed as a full-function heart/lung machine, while another perfusion system may be specifically designed as a ventricular-assist system. Although it may be possible to convert a perfusion system designed for one purpose to a perfusion system usable for a different purpose, such reconfiguration is generally difficult a nd/or time-consuming. In addition, perfusion systems often require a perfusionist operating the perfusion system to closely monitor many different parameters, and manually adjust the speeds of the various pumps in the system on a frequent basis to keep the various parameters in balance and within safe and desired limits. Accordingly, mechanisms are needed to help the perfusionist control the perfusion system with greater safety, accuracy and speed.
Automated fluid pump control modes in a medical perfusion system that help the perfusionist control the perfusion system include a Back Off Response Mode, a Flow Servo Mode, a Pressure Servo Mode, and a Master-Slave Servo Mode. In the Back Off Response Mode, pump""s speed is decremented to a new speed when an excessive flow rate or pressure condition is detected. The new speed is maintained until an additional decrement is required or until the Back Off Response Mode is exited. In the Flow Servo Mode, a pump""s speed is controlled to maintain a fluid flow rate indicated by a user as a setpoint. In the Pressure Servo Mode, a pump""s speed is controlled to maintain a pressure indicated by the user as a setpoint. In the Master-Slave Servo Mode, a slave pump receives an indication of a master pump""s speed, and the slave pump speed is controlled to maintain a specified percentage of the master pump""s speed.